The present invention pertains to a method of producing a plywood product and the product itself used for certain applications in the residential and commercial building industries, and more particularly as a trim and/or wall covering product for either exterior or interior use.
For the purpose of explaining the invention, its adaptation for use as an exterior wood trim product has been selected for domestic structures (homes) since at present it is the preferred application.
It has been almost exclusively the practice of architects and builders to employ solid wood, for exterior trim members, such as redwood and cedar for example, the trim being placed around doors, windows, wall sections, overhangs, soffits, etc. mostly for accent or to give a "finishing touch" to the homes.
The selection in the past of the solid types of woods was mainly done because of the desire to achieve a solid wood appearance, notwithstanding the inherent serious disadvantage of upkeep, in that such woods required repeated painting or staining and were subject to the ever constant problems of peeling, flaking and cracking. The disadvantages of these solid wood products were exacerbated by the continuous rise in cost of the wood involved, particularly due to the increase scarcity of cedar and redwood.
While the attempts to employ a plywood product in place of the solid wood was attractive due to the obvious substantial cost saving, plywood trim was not well received. This was due mainly because of the failure to give the appearance that the trim was a solid wood product, particularly as to the edges where not only the several plies were visible but also the customary edge openings could not be adequately filled and covered with paint or stain. This disadvantage when considered along with the fact that the plywood trim from a maintenance standpoint was no better, if not worse, than the solid wood trims led to a rejection of the plywood trim product.
Despite the failure of these earlier attempts to satisfy the industry's needs for an acceptable plywood trim product, because of the substantial cost saving it represented, the present invention sought to overcome each of the above mentioned drawbacks and others, and in fact has been successful in doing so.
This solution started with the recognition of selecting as the base plywood product a plywood generally similar to the type already on the market for other industrial uses, howbeit not for a trim product, such a product is manufactured and sold by Simpson Timber Company of Shelton Washington and marketed under the registered Trademark "Two Step" MDO, MDO being an acronym for a plywood base panel having a medium density overlay on one or both of its planar surfaces and employing a marine plywood type adhesive. A discussion of this product can be found in the American Plywood Association's brochure, Form No. B360F/Revised May 1988/4000. This product in the form employed by the present invention is known sometimes as a scarfed jointed panel, which is discussed and illustrated, along with other pertinent characteristics of the base plywood panel in a publication of the American Plywood Association entitled "U.S. Product Standard PS 1-83" Form No. H 850C/Revised, June 1987/6000. The term density refers to the amount of resin in the overlay, the resin being used for proper coating adhesives and the high content for moisture resistance.
The multi-step product generally is made by the selection of Douglas fir plies to form the substrate in a conventional manner, repairing any surface defects, sanding one or both of the planar surfaces and then covering these surfaces with a resin impregnated overlay by a hot pressing operation. This product is characterized by having a planar smooth surface, a surface that holds paint extremely well and a plywood substrate with a minimum of core gaps.
Such a product while having some very attractive features as a potential base board as a trim, still presented the problem of not giving the requisite solid wood appearance, particularly as to the ply edges on the long sides of the panel and even if the edge problem could be solved, there was no acceptable manner of being able to apply a paint, glaze or stain that would assure that both the planar surface and the edges would give the appearance of being a solid piece of wood and that both portions would yield a uniform maintenance free product.